Engine Displacement Calculator
Calculate engine displacement in cc, liters, and cubic inches.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Engine displacement is the total volume swept by all pistons in one complete stroke cycle. It directly correlates with engine power potential and is used to classify engines for racing, insurance, and registration purposes.
- Select your measurement unit. Choose millimeters for metric specifications (most modern engines) or inches for older American engines and aftermarket builds.
- Enter bore diameter. This is the inside diameter of each cylinder. For a stock engine, find this in the factory service manual or online engine specs.
- Enter stroke length. The distance the piston travels from top dead center (TDC) to bottom dead center (BDC).
- Select cylinder count. The number of cylinders in the engine.
Results show displacement in liters (the most commonly cited format), cubic centimeters (cc), and cubic inches (in³) for reference.
About the Engine Displacement Calculator
The formula is V equals pi divided by 4, times bore squared, times stroke, times the number of cylinders. This calculates the swept volume of one cylinder (a cylinder is a circular cross-section), then multiplies by cylinder count. For metric inputs (mm), the result in cubic centimeters (cc) equals the same calculation in centimeters (divide mm values by 10). A 4-cylinder engine with 86mm bore and 86mm stroke has a displacement of 1,998cc, or approximately 2.0 liters. This is a classic "square" engine where bore equals stroke.
Frequently Asked Questions
What is the difference between a square, oversquare, and undersquare engine?
A square engine has equal bore and stroke dimensions. An oversquare (short-stroke) engine has a larger bore than stroke, which favors high RPM and power at the expense of low-end torque, common in sports cars. An undersquare (long-stroke) engine has a smaller bore than stroke, producing more torque at lower RPM, common in trucks and diesel engines. Most modern passenger car engines are slightly oversquare.
How does displacement relate to horsepower?
More displacement generally allows more air and fuel into the cylinders, producing more power. A naturally aspirated engine typically produces 40-80 horsepower per liter. A modern turbocharged engine can produce 100-150+ horsepower per liter. An old muscle car V8 might only produce 35-45 hp/liter. The relationship is not fixed: engine tuning, induction type, compression ratio, and technology all affect power per liter.
Why do engines have different bore and stroke ratios?
Bore and stroke ratios are tuned for specific performance goals. Large bore, short stroke (oversquare) allows larger valves and higher RPM potential, favoring peak power. Small bore, long stroke (undersquare) increases gas velocity in the cylinder, improving combustion efficiency and low-end torque. Diesel engines are typically very undersquare for maximum torque and fuel efficiency at low RPM.
How do I find the bore and stroke of my engine?
Check your vehicle's factory service manual, the engine manufacturer's spec sheet, or search your engine code online. For example, "GM LT1 5.7L bore stroke" will return the specs. The bore and stroke are also engraved on some engine blocks or listed in emission compliance documents. For modified engines, the machinist or parts supplier can provide the actual measurements.